There exists a long-felt need for safe, inexpensive, easy-to-use, and reliable technologies for energy storage. Large-scale energy storage enables diversification of energy supply and optimization of the energy grid, including increased penetration and utilization of renewable energies. Existing renewable-energy systems (e.g., solar- and wind-based systems) enjoy increasing prominence as energy producers explore non-fossil fuel energy sources. However, storage is required to ensure a reliable, high quality energy supply when sunlight is not available and when wind does not blow.
Electrochemical energy storage systems have been proposed for large-scale energy storage. To be effective, these systems must be safe, reliable, low-cost, and highly efficient at storing and producing electrical power. Flow batteries, compared to other electrochemical energy storage devices, offer an advantage for large-scale energy storage applications owing to their unique ability to decouple the functions of power density and energy density. Existing flow batteries, however, have suffered from the reliance on battery chemistries that result in high costs of active materials and system engineering, low cell and system performance (e.g. round trip energy efficiency), poor cycle life, and others.
Despite significant development effort, no flow battery technology has yet achieved widespread commercial adoption. Accordingly, there is a need in the art for improved flow battery chemistries and systems.